1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor package with an externally connecting coupler, and more particularly, to a method of manufacturing a semiconductor package with an externally connecting coupler which is used as the ignition device for an internal combustion engine.
2. Description of the Related Art
FIGS. 5A to 5D illustrate the conventional method of manufacturing an ignition device having a semiconductor package structure, for use in an internal combustion engine.
First, a semiconductor device (IC) 2 is die bonded on a die pad of a leadframe 1, as shown in FIG. 5A. The leadframe 1 has a plurality of leads 3. The single lead located at the center extends from the die pad. The individual leads 3 are coupled to each other in an aligned state by a tie bar. Next, as shown in FIG. 5B, the semiconductor device 2 is connected to the leads 3 using a wire 4, i.e., so-called wire bonding is conducted. Thereafter, a mold package 5 for sealing the leadframe 1 including the die pad with the semiconductor device 2 thereon and the inner leads is formed using a resin, as shown in FIG. 5C. Subsequently, unnecessary portions of the leadframe 1 are cut off to complete an IC package (semiconductor package) 6 shown in FIG. 5D.
In the aforementioned manufacturing method, portions 7 of the leadframe 1, indicated by the hatching in FIG. 6, are cut off to separate the leads from each other after the mold package 5 is formed.
It may be considered to form the semiconductor package 6 and an externally connecting coupler 8 as one unit, as shown in FIG. 7, i.e., to plastically mold the portion including the mold package 5 and the coupler 8. However, it is impossible to form the mold package 5 and the coupler 8 as one unit because it is very difficult to cut off unnecessary portions 9 and 10 (the portions indicated by the hatching in FIG. 7) of the leadframe 1 after the mold package 5 and the coupler 8 are formed as one unit. That is, since the unnecessary portion 9 which forms the upper portions (the tie bar portion) of the leads 3 shown in FIG. 7 is embedded in the resin when the mold package and the coupler are formed as one unit, it can be cut off, for example, only after the unnecessary portion 9 is exposed by taking off part of the molding resin. A gap thus remained may be charged with the resin afterwards. However, the possibility of that the water contents enter in the package increases, and the reliability of the semiconductor package reduces. It is also difficult to cut off the unnecessary portion 10 which forms the lower portions of the leads because the lower end portions of the leads 3 are accommodated in the coupler 8 when the mold package and the coupler are formed as one unit. In that case, the unnecessary portion 10 must be cut off beforehand.
In the aforementioned conventional manufacturing method, it is impossible to form the mold package and the externally connecting coupler integrally as one unit in terms of the separation of the leads and support of the leads during the molding. That is, it is impossible to assure mutual separation of the leads and support of the individual leads in an aligned state before the mold package is formed.